Inverse code of string (Jilin University postgraduate entrance examination question)

Topic

A binary number , Reverse every bit of it , It's called the inverse of this number . Let's define the inverse of a character . If this is a lowercase character , Then it and the character ’a’ Distance with its inverse code and character ’z’ The same distance ; If it's an uppercase character , Then it and the character ’A’ Distance with its inverse code and character ’Z’ The same distance ; If it wasn't for the above two situations , Its inverse is itself . Take a few examples ,'a’ The opposite of ’z’;‘c’ The opposite of ’x’;‘W’ The opposite of ’D’;‘1’ It's the inverse of ’1’;’%‘ It's the inverse of ’%’. The inverse of a string is defined as the inverse of all its characters . Our task is to compute the inverse of a given string .
（’%‘ It's the inverse of ’%' The original question is dollar sign , But I can't type it here , Just make an example to show whether the inverse code of the symbol character is itself ）

Input description :
Each input line is a string , The string length does not exceed 80 Characters . If the input is only !, End of input , No need to deal with .

Output description :
For each string entered , Output its inverse code , One line per data .

Example 1
Input
Hello
JLU-CCST-2011
!
Output
Svool
QOF-XXHG-2011

What to pay attention to

Input only "!" It means that the characters you enter in this line are only ! Instead of just entering one !
This question is in Chinese string Just do it , Never mind his length limit

Thinking and test code

1. The distance can be calculated directly with similar s[i]-'a’ It means , This subtraction yields two char Between ASCII Code difference , That's distance
2. Only !, You can set one first bool Variable end by true, Then check whether the string is all composed of ! form , If you find something different from ! The characters of . Then put the end Set to false that will do . Then judge end, If it is true End
The code is as follows （ Has passed Niuke network OJ determine ）

#include<iostream>
#include<string>
using namespace std;
string letters = "abcdefghijklmnopqrstuvwxyz";// Lowercase letter set 
string letters1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";// Capital alphabet 
int main() {
    

	while (true) {
    
		string s; bool end = true;
		cin >> s; 
		for (int i = 0; i < s.size(); ++i) {
    
			if (s[i] != '!') end = false;
		}
		if (end)break;// The string is all ! Out of the loop 


		for (int i = 0; i < s.size(); ++i) {
    
			if (islower(s[i])) {
    
				int distance = s[i] - 'a';
				for (int i1 = 0; i1 < 26; ++i1) {
    
					if (distance == 'z' - letters[i1])
					{
    
						s[i] = letters[i1];
					}
				}
			}

			if (isupper(s[i])) {
    
				int distance1 = s[i] - 'A';
				for (int i2 = 0; i2 < 26; ++i2) {
    
					if (distance1 == 'Z' - letters1[i2])
					{
    
						s[i] = letters1[i2];
					}
				}
			}

			cout << s[i];
		}
		cout << endl;// Line break 
	}
	return 0;
}